DE19730466A1 - Pressure-resistant and thermally stable insulating coatings for hollow bodies and a process for their production - Google Patents

Abstract

The invention relates to a method for producing insulating coatings for hollow bodies. Said insulating coatings have polyurethane and/or polyisocyanurate groups, and are produced by reacting a) one polyisocyanate component with b) at least two compounds with hydrogen atoms which are active towards isocyanates and c) catalysts, optionally in the presence of d) other auxiliary agents and additives. The inventive insulating coatings are characterised in that organic or mineral hollow microspheres with an average particle size of between 5 and 200 mu m and a density of between 0.1 and 0.8 g/cm<3> are added to at least one of the components a) to d). The invention also relates to the use of the inventive insulating coatings for pipes used in offshore applications.

Description

The invention relates to polyurethane and / or polyisocyanate groups Insulating coatings for hollow bodies, in particular pipes, and a method their manufacture.

As is known, u. a. PUR foams and PUR elastomers for the insulation of Oil and gas pipelines used in the off-shore area.

EP-A 636 467 describes how a thick-layered layer is produced in one operation PUR coating of rotating bodies such as rollers and pipes can be. Among other things is also the pipe coating with syntactic PUR slurries known for insulation.

The profile of requirements for such insulation materials is being opened up by new ones Oil fields significantly increased at greater depths. Among other things must be heat resistant speed of these materials from previously 120 ° C to 160 ° C and the compressive strength of previously 50 bar (500 m diving depth) can be increased up to 250 bar (2500 m diving depth).

Polyurethane materials described above are resistant to permanent temperature however limited to approx. 120 ° C.

The object of the present invention was therefore to provide insulating coatings for pipes find a heat resistance above 120 ° C and a pressure resistance above Have 50 bar.

Surprisingly, it was found that the combination of Polyiso cyanurate reaction masses with temperature and pressure stable micro hollow bodies desired requirements are met and for straight and slightly curved Pipes the economical spin coating mentioned in EP-A 636 467 procedure can be applied. Pipe elbows and connections can be used with same raw material base can be produced in the mold.  

The invention therefore relates to a process for producing insulating coatings for hollow bodies having polyurethane and / or polyisocyanurate groups by reacting

• a) with a polyisocyanate component
• b) have at least two hydrogen atoms active with respect to isocyanates the connections and
• c) catalysts optionally in the presence of
• d) further auxiliaries and additives,

in the at least one of components a) to d) organic or mineral hollow microspheres with an average particle size in the range from 5 to 200 μm and a density in the range from 0.1 to 0.8 g / cm ³

be added.

The coatings according to the invention are suitable for the rolls or tubes, such as they in the steel industry, conveyor and transport industry as well as in the paper industry be used. In addition, pipes with an outer coating for the industrial as well as tubes with inner coating for hydraulic conveying of abrasive goods. If necessary, you have to be coated Provide surfaces with an adhesion promoter beforehand.

However, pipes or other hollow bodies can also be made using the new method by coating a removable core. In this case you have to Apply a release agent to the core or wrap it with a release film. Finally, the new method can also be used to pipe with a Thermal insulation jacket made of rigid polyurethane foam.

It has been shown that the new process is not only for the inside and outside Coating of rotationally symmetrical bodies is suitable, but that too  Bodies are coatable, which differ over length and / or cross section Have diameter.

The method according to the invention is particularly suitable for the coating of Pipes for the off-shore area, especially for pipes with a depth of more than 500 m, the pressure load of greater than 50 bar and a temperature of greater Exposed to 120 ° C.

The reaction components are liquid reaction mixtures massive or foamed, optionally having isocyanurate groups preferably reacted hard polyurethane plastics. It is a matter of Mixtures of organic, preferably aromatic polyisocyanates with having at least two hydrogen atoms active with respect to isocyanates Compounds, especially organic polyhydroxyl compounds, the Polyisocyanates for the production of pure polyurethanes, based on the Hydroxyl groups, in approximately equivalent amounts and for the preparation of isocyanurate modified polyurethanes are used in excess. This means that the isocyanate index is generally within the range of 90 to 2000, preferably 100 to 1800. The "isocyanate index" here is the Number of isocyanate groups of the polyisocyanate component per 100 hydroxyl groups to understand the poly-hydroxyl component.

Suitable systems which have reacted to give polyurethanes are described, for example, in DE-PS 16 94 138 described while as casting compounds that are modified to isocyanurate React out polyurethanes, systems according to DE-PS 25 34 247 are used can.

The casting materials can be the customary auxiliaries and additives, ie catalysts for the isocyanate addition reaction such as dimethylbenzylamine, dibutyltin dilaurate or per-methylated diethylenetriamine, catalysts for the trimerization of isocyanate groups of the type described in DE-PS 25 34 247, or fillers such as, for example, glass fibers , Aluminum hydroxide, talc, chalk, dolomite, mica, heavy spar or wollastonite (CaSiO ₃ ) can be added.

It is essential to the invention, however, that mineral and or pressure-resistant, temperature-resistant plastics with a hollow micro structure of 0.5% up to a maximum filling, without creating additional cavities, based on the total weight of the reaction components.

The maximum filling is calculated as follows:

ρ _{hollow body} = density of the micro _{hollow body}
ρ _bulk = mean bulk density of the hollow micro-bodies
ρ _PUR = density of the polyurethane matrix
Free space = remaining space between filled, maximally compressed hollow bodies
Free space = ρ _hollow -ρ _bulk .

In order to achieve a flow of the matrix during the reaction, there must be at least 1% by weight of excess matrix compared to the free space. This results in the following formula as the maximum filling:

Minimum PU quantity per 100 g hollow body
Minimum matrix amount = ρ _PUR . (1 / ρ _bulk -1 / ρ _{hollow body} ) .1.01.100.

The minimal PUR matrix calculated according to the above formula has a preferred one Key figure between 1000 and 1600.

Mineral hollow microspheres are preferably used. Mineral microspheres with a density range of 0.1 to 0.8 g / cm ³ and an average particle size of 5 to 200 μm and a pressure resistance greater than 50 bar are particularly preferred. Hollow bodies of this type are commercially available, for example, under the names Q-CEL® (Omya GmbH) and Scotchlite® Glass Bubbles (3M Deutschland GmbH).

The additives essential to the invention can be used in the production of the casting compounds both the polyisocyanate component and the polyhydroxyl component or can be added both in advance and immediately before the reaction.

The insulation layer is preferably produced on pipes either after the rotary coating method described in EP-A-636 467 or after the conventional casting in molds with the corresponding pipe parts as Insert.

The insulating coatings produced according to the invention usually have a density of less than 0.9 g / cm ³ , preferably a density of between 0.5 and 0.8 g / cm ³ . The coefficient of thermal conductivity for the insulating coatings produced according to the invention is advantageously less than 0.180 W / mK. Furthermore, the insulating coatings according to the invention have a very good pressure resistance greater than 50 bar and a high thermal stability of greater than 120 ° C.

Examples

In the following examples, both pipe coatings according to the Rotary coating process as well as the classic casting process wrote.

General manufacturing instructions

The components A and B listed in the examples were carefully Mix the individual components and then evacuate for the purpose Degassing manufactured individually before dosing. The dosage was over special, fillable low-pulsation dosing pumps and needle valves in one special low pressure mixing head.

Depending on the process, either a film nozzle (rotary coating) or a round nozzle (classic casting) partially with attached hose, the reactive Mixture applied to the pipe. The processing temperatures of each Depending on the viscosity, components were set at room temperature up to 70 ° C. The pipes were always at room temperature, were sandblasted and partly with pretreated by a marketable adhesion promoter. The shapes were both undecorated heats as well as tempered to 80 ° C, used to cure the reactive poly accelerate urethane mixture. After demolding and / or only after The pipes could already cool down to approx. 35 ° C on the coating in one appropriate soft bed (wooden beam prism plus 40 min thick soft foam stripes). The first physical tests were carried out no earlier than 24 Hours after the casting process.

1. Pipe insulation coating using the spin coating method

Here, the reactive polyurethane mixture is poured onto the rotating tube via a film nozzle guided in the direction of the longitudinal axis. The feed of the nozzle is adjusted so that the desired coating thickness is achieved with constant output.

Steel tube with an outer diameter of 230 mm
Film nozzle with a width of 200 mm
Output of 12 l / min = 8.4 kg / min
Coating thickness of 45 mm
Coating speed of 308 mm / min
Density of the insulating layer 0.7 g / cm ³
Pouring time 8-15 seconds
Thermal conductivity 0.14 W / mK
Pipe speed 28 rpm

In the following examples, both the polyethers used, the Isocyanates as well as the key figure varies.

example 1 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
1.5 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

150 parts by weight of polyisocyanate with 31.5% NCO
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250.

The test for compressive strength (test specimen: cubes of 100 mm edge length) at 200 bar in water at room temperature resulted in a test time of 24 hours Water absorption of less than 3 g for the entire test specimen. Checking on  Thermal stability (test plates 20 × 100 × 10 mm) resulted in storage of 4 months at 200 ° C no visible changes and no loss of properties.

Example 2 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100% propylene oxide and glycerin. 2.0 parts by weight of zeolite 50% in castor oil
3.5 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

150 parts by weight of polyisocyanate with 31.5% NCO
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

Example 3 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
1.8 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 150 parts by weight of polyisocyanate and
12 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1150

Example 4 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
1.8 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 162 parts by weight of polyisocyanate and
13 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
50 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

Example 5 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100% propylene oxide and glycerin. 2.0 parts by weight of zeolite 50% in castor oil
3.5 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 150 parts by weight of polyisocyanate and
12 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1150

Example 6 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100% propylene oxide and glycerin. 2.0 parts by weight of zeolite 50% in castor oil
3.5 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 162 parts by weight of polyisocyanate and
13 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
50 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

2. Pipe coating after casting

Here, a pretreated pipe section is opened into a one treated with a release agent 80 ° C tempered mold inserted, the mold closed, 10 ° inclined and on the filled the lowest point over a hose until the reacting poly urethane mixture at the highest point, a riser emerges from the mold. By Clamping the hose and loosening it from the mixing head will form the sprue sealed and the mixing head can be rinsed with component A.

Steel tube with an outer diameter of 230 mm
Coating length 56 cm
Round nozzle with a diameter of 22 mm
Output of 10 l / min = 7 kg / min
Coating thickness of 45 mm
Density of the insulating layer 0.7 g / cm ³
Casting time 140-200 seconds
Thermal conductivity 0.14 W / mK
Fill time 135 seconds.

In the following examples, both the polyethers used, the Isocyanates as well as the key figure varies.

Example 7 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
0.6 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

150 parts by weight of polyisocyanate with 31.5% NCO
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

Example 8 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100% propylene oxide and glycerin. 2.0 parts by weight of zeolite 50% in castor oil
0.9 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B
150 parts by weight of polyisocyanate with 31.5% NCO
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

Example 9 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
0.6 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 150 parts by weight of polyisocyanate and
12 parts by weight Castor oil, Brazil no. 1, NCO calculates 29% .3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1150

Example 10 Component A

100 parts by weight of polyether, OH number 36, polyaddition of 83% propylene oxide and 17% ethylene oxide with trimethylpropane
2.0 parts by weight of 50% zeolite in castor oil
0.6 parts by weight activator, solution of alkali acetate in diethylene glycol
40 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 162 parts by weight of polyisocyanate and
13 parts by weight Castor oil, Brazil no. 1, NCO calculates 29% .3.0 parts by weight of 50% zeolite in castor oil
50 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250

Example 11 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100% propylene oxide and glycerin. 2.0 parts by weight of zeolite 50% in castor oil
0.9 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 150 parts by weight of polyisocyanate and
12 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
45 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1150

Example 12 Component A

100 parts by weight of polyether, OH number 56, polyaddition of 100%
Propylene oxide and glycerin. 2.0 parts by weight of 50% zeolite in castor oil
0.9 parts by weight activator, solution of alkali acetate in diethylene glycol
35 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Component B

Prepolymer
from 162 parts by weight of polyisocyanate and
13 parts by weight Castor oil, Brazil no. 1, NCO calculates 29%
3.0 parts by weight of 50% zeolite in castor oil
50 parts by weight of hollow glass microspheres, average density 0.32 g / cm ³

Key figure 1250.

Claims (6)

1. Process for the production of polyurethane and / or polyisocyanurate group-containing insulating coatings for hollow bodies by reacting

• a) with a polyisocyanate component
• b) at least two hydrogen atoms active against isocyanates on pointing compounds and
• c) catalysts optionally in the presence of
• d) further auxiliaries and additives,

characterized in that at least one of components a) to d) organic or mineral hollow microspheres having an average particle size in the range from 5 to 200 µm and a density in the range from 0.1 to 0.8 g / cm ^{3 are} added. 2. The method according to claim 1, characterized in that mineral micro hollow spheres are added. 3. The method according to any one of claims 1 to 2, characterized in that Hollow microspheres with a pressure resistance of over 10 bar can be added. 4. The method according to any one of the preceding claims, characterized in that that the hollow bodies are pipes. 5. Insulating coatings containing polyurethane and / or polyisocyanurate groups for hollow bodies from the reaction

• a) with a polyisocyanate component
• b) at least two hydrogen atoms active against isocyanates on pointing compounds and
• c) catalysts, optionally in the presence of
• d) further auxiliaries and additives,

characterized in that the insulating coating contains hollow microspheres with an average particle size in the range from 5 to 200 µm and a density in the range from 0.1 to 0.8 g / cm ³ . 6. Use of an insulating coating according to claim 5 for the coating processing of pipes for the off-shore area.